1846 



ENCYCLOPEDIA OF I'KACTK'AI. HOKTICULTURE 



nius decay going oti rapUlly onousli to 

 make sufficient plant food available for 

 the needs of the growing crop. In soils 

 containing low percentages of luiiiius. 

 this means the plowing under of vegetable 

 materials, such as manure, or cover 

 crops, followed by suitable tillage to en- 

 courage the processes of decay. In soils 

 well supplied with vegetable, or organic 

 matter, proper tillage alone is sufficient 

 to maintain these favorable conditions. 



riant Food Re(nilrenients of Fruit Crops 



The amounts of the different plant 

 food elements which are found, by anal- 



ysis, in the mature crop are generally 

 considered a measure of the quantity of 

 these materials which the crop took from 

 the soil. If there are no losses due to 

 other sources than the growing of the 

 crop, these amounts then represent the 

 yearly drain upon the total food su])ply 

 of the soil. Table III shows the amounts 

 of the critical elements of fertility which 

 are found in the indicated yield of each 

 of some of the common fruit and garden 

 crops. 



(Taken from Van Slyke's "Fertilizers 

 and Crops.") 



TABLE III 

 Plant Food Reqniroiii.eiits of Different Fruit and Veftetable Crops 



Variety of Fruit 



No. of Trees 

 per acre 



Nitrogen 

 lbs. 



Pliosphoric 



Acid (Pj05) 



lbs. 



Potash 

 (K,0) 

 lbs. 



Lime 



(CaO) 



lbs. 



Apple 



Peach 



Pear 



Plum 



Kind of \'egctablc 



Cabbage 



Onions 



Cantaloupes 



Tomatoes 



Watermelons 



35 

 120 

 120 

 120 



Yield 

 per Acre 



10 tons 

 300 bu. 



5 tons 

 2.50 bu. 



10 tons 



52 

 75 

 30 

 30 



60 

 39 

 22 

 30 

 34 



14 

 18 



20 

 1,5 

 S 

 11 

 12 



55 

 72 

 33 

 38 



80 

 38 

 40 

 .53 

 60 



57 



114 



38 



41 



The figures given are, in each case, for 

 the yield of edible material, and do not in- 

 clude the plant food used by the non- 

 edible leaves, stalks, etc., it being assumed 

 that these will be returned to the soil 

 each year. The plant food used in mak- 

 ing the wood growth of fruit trees is, of 

 course, not accounted for in these cal 

 culations. 



Value of Legutiiinoiis Cover Crops 



Reference has been made above to the 

 value of a sufficient supply of vegetable 

 matter in the soil, in order that its active 

 decay may insure an ample supply of 

 available plant food. Humus performs 

 many other important beneficial functions 

 In the soil. It affects very beneficially 

 the physical proijerties of the soil, in- 

 creasing the ease of tilth, moisture-hold- 

 ing capacity, capacity to absorb heat, etc., 

 and decreasing the tendency to "puddle" 

 when wet and "bake" when dry. 



Any farm crop which is grown for the 



sole purpose of plowing it under to in- 

 crease the supply of organic matter in 

 the soil is known as a "green manure." 

 Green manures affect the soil beneficially 

 in many ways. Some of the possible bene- 

 fits are: (1) The addition of vegetable 

 matter or "humus," with its attendant 

 beneficial effect upon the physical and 

 chemical properties of the soil. (2) In- 

 creasing the nitrogen content of the soil 

 by fixation of nitrogen of the air, when 

 leguminous crops are used as the green 

 manui-e. (3) Using surplus available 

 plant food, .which might otherwise be 

 lost. (4) Plant food from lower depths 

 may be brought nearer to the surface and 

 made available for subsequent crops. 



The kind of crop which may best be 

 used as a green manure depends upon 

 which one or more of these beneficial ef- 

 fects is most desired. If the addition of 

 humus, or an increased supply of decay- 

 ing vegetation, is the only necessity, then 



